Display technology has developed rapidly in recent years. Liquid crystal displays (LCDs) have become part of human being's life. Typically, an LCD includes an array substrate, a counter substrate, and a liquid crystal layer sandwiched between the two substrates. The array substrate has a thin film transistor (TFT) formed thereon. Liquid crystal molecules in the liquid crystal layer are driven and controlled by an electric field, which is generated between a pixel electrode connected to TFT and a common electrode, so that display of images is realized.
Conventionally, a three-mask process is used to manufacture the array substrate. The process includes forming a rough surface on top of photoresist layer. Because of roughness of top surface of photoresist layer, pixel electrode formed on photoresist layer later could be broken to have stripping solution contact photoresist layer during stripping treatment. Formation of rough surface on top of photoresist layer increases stripping efficiency. However, while rough surface is formed on top of photoresist layer, rough surface is also formed on top of passivation layer. Roughness of rough surface generated on top of passivation layer cannot be reduced using water, stripping solution, or air gun, and thus influences process stability and display quality.